The biomechanical impact of hip movement on iliofemoral venous anatomy and stenting for deep venous thrombosis.

BACKGROUND: Stenting of the iliofemoral vein may be an effective treatment to improve post-thrombotic symptoms. Iliofemoral vein stents have requirements different from those of lower extremity artery stents, and there is a paucity of literature regarding the biomechanical motion of the iliofemoral vein.

METHODS: In a novel cadaveric model, stents were bilaterally inserted into the veins in the iliofemoral region. The veins were pressurized and underwent computed tomography angiography at various hip angle positions. In addition, 21 patients with iliofemoral vein disease had supine computed tomography angiography before and after stenting. The stents and vasculature were reconstructed into three-dimensional geometric models to quantify stent deformations and the interaction between the iliofemoral vein, inguinal ligament, and pubis bone due to hip flexion-extension.

RESULTS: In the cadavers, from supine to 30 to 45 degrees and 50 to 75 degrees of hip flexion, iliofemoral vein stents became less compressed (4.5% minor diameter expansion), and the inguinal ligament was separated from the iliofemoral veins by 1 to 3 cm in all hip positions. In the patients, the pubis compressed 47% of femoral veins; 78% were within 3 mm of the pubis. There was also evidence of contrast-enhanced flow disruption at the superior ramus.

CONCLUSIONS: The cadaver and clinical evidence shows that contrary to widely accepted dogma, the common femoral vein is not compressed by the inguinal ligament during hip flexion but rather by the superior ramus of the pubis during hip extension, which may have an impact on future stent design and influence deep venous thrombosis treatment strategies.